Support is requested to expand the existing four-story Laboratory Animal Facility (LAF) in the West Building of the Fox Chase Cancer Center by adding a four-floor wing onto the current facility. This addition of 25,290 gross square feet will add 12,910 net square feet of animal research space. Over 6000 square feet of space is utilized for air handling equipment which supports the combined new facility (old facility plus the proposed addition). This addition, combined with renovation of the existing facility (planned for 2006-2007) and increased use of high density microisolator cages (already begun), will increase the research mouse capacity to 25,600 cages. At our current and expected rate of use this expansion will satisfy the animal research needs of research investigators at FCCC until 2010. Capabilities of the current centrally administered AAALAC accredited program in Philadelphia have been exceeded and much of the existing facility is overcrowded and lacks a secure microbiological barrier, placing studies at risk of being invalidated due to infections. The proposed addition will correct deficiencies in animal space, and provide a high quality mouse research barrier facility with space for expanding genomic services in a setting of stringent microbiological security. Located immediately adjacent to the existing facility, it will be able to utilize central cagewashing and support services. It will also add a small cagewash area for the basement woodchuck and duck area to better separate them from the barrier mouse research facilities. This expansion will provide: -2,032 nsf of quarantine space for the health evaluation and rederivation of incoming mice. -4,967 nsf of additional mouse holding rooms -1,078 nsf of additional procedural laboratories -additional cage washing and procedural areas for support to woodchuck and duck viral hepatitus studies -autoclave, gowning and sterilization capability at the entry to each research mouse holding area In addition to the above, the expansion will house mechanical space for the quarantine facility and air handling for the entire LAF. The campus is currently overdeveloped making available space for mechanical support equipment critical. Therefore, cooling towers will be located on the roof and are necessary for redundant chilled water capacity supporting the LAF. Rooftops become prime real estate for cooling towers to support this rapidly growing research complex.